on which to establish service, often via a web page. A unique code is first indicated or displayed to the customer via the web site, then an automated call is then placed to the supplied subscriber telephone number. To validate the transaction, the code entered via the telephone keypad must match. This method is used by Google Voice and online banking services such as Lloyds TSB. Database check Certain services offer to check telephone numbers alongside other personal details, gained from various public sources e.g. the Electoral roll and from the imprints left on by their activities, for examples from transactions made using credit cards. The advantage of a database check is that the lookup can be very quick (sub 1s), however no databases exist to cover all telephone subscriber lines internationally, with mobile telephones being particularly problematic to trace - especially Pay as you go (phone) (non contract) arrangements which often have no registered owner. Some databases are very detailed and can correlate telephone numbers with physical addresses, e-mail addresses, ownership and sometimes even personal details. Such detail can help with combating fraud as well as allowing greater understanding of a customer base. At the other end of the scale, other database checking services might only check a telephone number against the allotted telephone number banks and therefore only indicate if a number is in a range that might be active and are therefore inconclusive. Check for valid number format A JavaScript function can check to see if a phone number is a valid format, i.e., is numeric, starts with a valid set of numbers ("0" for local, or an international dialing prefix followed by a valid country code and is not too short to be a phone number. At first a JavaScript function is used to clear out any spacer characters. Next, a function is employed to check if the phone number contain only numbers, last the length of the string is checked permitting only phone numbers with an allowable number of digits for the country. It is prudent to carry out such checks even if a further method is employed in addition, so that telephone numbers to avoid wasting time and resource on numbers that are clearly not in a correct format to qualify as a telephone number, e.g. too short. Other methods of verification Some other methods that are being employed today are: Sending an OTP